3D printing is any of various processes used to make a three-dimensional object. Additive processes are used in which successive layers of material are laid down under computer control. These objects can be of almost any shape or geometry, and are produced from a 3D model or other electronic data source.
A large number of additive processes are now available. One type of process is an extrusion process that produces an object by extruding small beads of material which harden immediately to form layers. Various polymers can be used as the building material, including acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polylactic acid (PLA), high density polyethylene (HDPE), PC/ABS, polyphenylsulfone (PPSU) and high impact polystyrene (HIPS). In general, the polymer is in the form of a filament that can be fed to an extrusion nozzle head. Metal can also be used, where metal wire is fed to the extrusion nozzle head. The extrusion nozzle head is heated to melt the material, which is then deposited out the extrusion nozzle head. The extrusion nozzle head can be moved in both horizontal and vertical directions by a controlled movement mechanism, such as an XYZ gantry. The movement mechanism moves the extrusion nozzle head according to a computer program, such as a computer-aided manufacturing (CAM) software package running on a microcontroller, and the object is built from the bottom up, one layer at a time.